DESCRIPTION(As provided by Applicant): Neural synchronization in response to external stimuli is a critical component of many sensory transduction pathways. In the proposed project, detailed electrophysiological studies would be conducted on the responses of the two crayfish caudal photoreceptors (CPRs) to mechanical stimuli under various illumination conditions. The CPRS, which are both primary photosensitive cells and mechanosensory interneurons, have not yet been studied together in their responses to various stimuli. The proposed dual electrode recordings would provide new understanding of the mutual synchronization of the two CPRs with each other as well as with external sensory stimuli. Investigation of the CPR responses at various points in the crayfish nerve cord will reveal the changes in coherence between the cells' firing at various levels of signal integration. Dual recordings of CPR response noisy periodic mechanical stimuli will also be investigated, in order to extend studies of stochastic resonance previously performed on one CPR cell to an exploration of the role of environmental noise in modulating the coherence between the two cells' firing rates.